Blender 2.8 Object and Background plane disappear
That is your camera clipping, it will only show object in a certain distance of the camera. You need to make it where it will show objects further away. in your screen shot, in the menu to the right you will see the clipping settings. Set the clipping end at 1500 or so and you should see everything.

Okay try going to object mode and opening the N bar on the right. fin the view tab and click it. That will open the scene clipping. you can try upping the end clipping on it, and see if that helps.

Select the camera object, then to the right where the where all the the icons are select the green camera and you will find the camera clipping. Up the end value there.